I agree with John of Brisbane that the ABC programs aren't too hot at matching up lyrics to staff notation. My suggestion to look at the ABC site was mainly for the 'shorthand' the system provides for entering music. I find I can usually enter a tune in ABC much faster than I can produce it in NoteWorthy. After entering as an ABC file, I then run it through one of the ABC to MIDI converters to produce a file I can import into NoteWorthy (I use Henrik Norbeck's ABCMus - registration a lordly $10 US the last I checked). Then I either import the lyrics from a text file or enter them directly into NoteWorthy.

Most ABC programs are supporting at least 4 voices now. But my main reason for mentioning ABC was its cross-platform capabilities, since availability for MAC was also mentioned in the request. Since I don't have access to a MAC, I can't remark on its capabilities, but Phil Taylor's BarFly seems to be a well received MAC program on the ABCUsers' List.